First, if you submitted cheek scrapings or other DNA material to the National Geographic Genographic Project, the 12 markers returned to you are simply not enough to provide you with accurate matches to your relatively recent family members. My understanding is that those 12 markers only help the Genographic Project understand your ancestors path/s from thousands, even millions, of years ago.

Whenever possible, try to have a 37 marker result, ideally a 67 marker test is the best to aim for. The more markers the more expensive the test, but also the more accurate the match (if and when one is found).

FamilyTreeDNA (see their link below) provides all levels of tests and is affiliated to the Genographic Project. Bonus: If you did the 12-marker test for the Genographic Project, FamilyTreeDNA.com can access that same test and extract the higher levels for a reduced "upgrade" fee - without further testing from you.

Second, none of these DNA tests identify illness or disease, they only prove or disprove a match with someone else. Why that would be a concern for anyone is rooted in misunderstandings and previously misleading information.

Third, at least one of these tests, at the 37 marker level, is free. Simply send for the kit, provide the DNA material (a painless, non-invasive and simple procedure), return the kit and wait for the results.

Fourth, understand that this process is in its infancy. The biggest database contains perhaps 200,000 results so far, and will keep growing. Because you may not find a match in this database does not mean you will not find a match in another... EVEN IF YOU FIND A MATCH NOW you may - and should - come back at a later date to check for other matches as the database grows.

Fifth, add your information and contacts to the database and document your findings and matches. You should prepare yourself for the day when someone finds you a perfect match, be able to look at what is presented objectively, and say with some degree of certainty whether this newcomer is related.

Sixth, wherever you live in the world, I encourage you to have the test/s done and place the results in any or all of the databases. The more people participating, the more who will find their true pedigrees, lost branches/individuals, and missing generations.